Heat exchangers are used to cool electronic components generating heat. In one example, a cold plate assembly used in connection with radar transmit and receive modules is made of aluminum and includes therein copper heat pipes.
One problem with copper is that it is heavy, which is a concern in ship and airborne applications. Historically, aluminum can be used for the cold plate housing, allowing weight optimization, but when integrated with the copper heat pipe can introduce the possibility for galvanic corrosion. When solder, or other materials, are used as the barrier material between the cold plate housing and heat pipe, voids introduce thermal resistances, contribute to local galvanic corrosion opportunity, and reliability problems. Moreover, the current process of making the cold plates limits design flexibility and is labor intensive and expensive. Copper is also becoming increasingly costly.
Aluminum heat pipes available on the market today suffer from reduced thermal efficiency. When integrated with aluminum cold plates, the dissimilar metal problem is solved and the possibility for galvanic corrosion is reduced to, but the result is reduced thermal performance. This reduced performance limits applications. Additionally, these heat pipes suffer from poor reliability and manufacturability issues. Attempts at plating either aluminum or copper cold plates and copper heat pipes with a tin-lead composition to eliminate corrosion resulted in additional thermal interfaces, an added expense, and additional manufacturing steps.
Given that in a radar assembly there can be thousands of cold plates, a new cold plate technology would be beneficial.